I'm in the process of looking for an auxiliary fuel tank for my '05 Duramax. I think I have decided on a 60 gal toolbox/tank combo made by RDS and sold by Northern Tool. The tank has fittings for either gravity flow, or a pickup tube fitting for use with a pump. They also make a kit that installs between the low point gravity fitting and the filler hose that has a check valve built into it that shuts off the auxiliary tank when the OEM tank is full and fuel starts backing up the filler hose. Anyone have any experience with this setup?? In actuality I would prefer hooking it up to a pump over which I have control. Where can I purchase a small 12 volt pump to pump diesel. I understand that a regular automotive type fuel pump (i.e. Holley) will not stand up to diesel fuel.

Roy, I work for a tank distributor and see a lot. Gravity is bad news, and may be illegal in some areas. If a hose or connection gets a leak, you lose the tank load of fuel on the road. A fuel pump is better, but how to you know when to shut the pump off? We have a mechanic at work that ran his over three times, once in our gravel parking lot at work, once at home in his drivway, and once at a "Home-Depot" parking lot! That brought out the police and fire department!
If you do use a small electric pump, tee into the 2" filler pipe on your main tank, also add a second tee to vent both tanks together so they are common, plus you must also vent your aux tank to atmophere.
I run a "Transfer-Flow" 98 gallon tank, which is automatic transfer of fuel from the aux to the main tank. I have a read out in my cab that shows when the pump is on, how many gallons are in each tank, plus total gallons of both. This gives me a total of 132 gallons and allows me to shop for fuel a little. I save about 40 cents a gallon between my Home State and where my Daughter lives, so when we visit we fill up.
I urge caution with you installation because of what one of my co-workers experienced above.
Wish you well, and hope this information helps.

I have a 75gal. tank. That I have a pump off a 2000 diesel chevy. I made a section of pipe that tapes in to the fill hose. It has two hose barbes in it the closest to the main tank is the return to aux. And the upper one is the fead from the aux. this way if you foget to shut it of when main reads full it returns to aux. I also put A vacume brack befor the pump to stop a sifon from forming. The vacume brack I got at West Marine. Also wired the switch to ign. hot. Have forgotin it more than once with no over flows. Good luck Mike

Thanks for the input guys. I do however have a couple of questions. I bought a 12V pump (6 psi/35 gph) made by a company called Facet which will pump all fuels, oil, etc. How does this compare say to the pump that comes with the Transfer Flow system ? Tom.....Is it okay to tie the aux tank vent into the OEM tank ventline that comes up to the truck filler neck? Mike....where did you find the vacuum break for the pump at West Marine, I couldn't find one. I do need it, as my pump goes straight through when off and would siphon fuel out of the aux tank.

Roy I suppose you could vent the aux to the main tank vent hose, but at least use the 2" fill pipe for product flow. Also make sure your aux tank has a proper in breathing and out breathing vent to atmosphere. [img]smile.gif[/img]

With the 2 pipes going from the aux. tank to the main tank, (one the fuel pump line the second the overflow or return line used only if the pump doesnt shut off), the tank vents through the trucks approved venting system that would meet emissions.

I found the vacume brack buy the gas hose and filters and things. I also found it on ther web site but have not been there in some time and can't remember how I found it there.
As for the pump the gal. per min. just controles the speed of fill up. I do not know my pumps rate. But i start it when I git down to about a half. It will fill up the main i about a half hour or so. all this while driving by those so called ezey on ezey of stops.

For mine, I used a 12 v automobile fuel pump that only pumps a very small amount per minute ( about 45-50 min. for 30 gal) thru a 5/15" line. I come out of the tank thru a small filter, to a 12v. 1/4" s.s. solenoid valve (from Grainger supply), to the fuel pump, to the main tank by a Tee into the 5/8" vent tube in the fill neck. The low flow does not interfere with the venting. As for controlling the flow and not overflowing, I don't transfer fuel until the main tank is more than 30 gal. below full.

HERE'S HOW THE FINAL INSTALLATION WENT. I bought the 60 gallon auxilary tank/toolbox combo from Northern Tool for $499 plus $100 shipping. It fit right in forward of the wheel wells of my short bed 2500HD. I did put a 2X4 on edge across the front of the bed to space it out a little more when opening the toolbox lid. I used a FACET brand solenoid type pump that I bought new on ebay for $28. but is available from JC Whitney for $42. I also bought a filler hose kit from Northern Tool for $55. which has the tee for tapping into the 2" truck rubber filler hose, as well as a ball type shutoff valve and assorted hoses and clamps. I decided against a gravity fill for safety reasons as Tanker described above. My auxiliary tank came with a fuel gauge, pickup fitting, a return fitting, a vent fitting, and a drain (gravity) fitting. I bought a anti-siphon pickup fitting from West Marine for $13., as my pump was straight through in the fuel flow direction. I used a 1 1/2" hole saw to cut a hole in the inside corner of my bed in the vicinity of the filler hose, then took a piece of 5/16" fuel line and split it length wise to make a grommet to fit around the metal edge of the hole. The 2" rubber truck filler hose was then cut and the inlet tee with a 3/8" barb fitting in it was installed. I then ran a 3/8" hose from the tank pickup fitting to the pump, and from the pump to the 3/8" barb fitting in the filler hose tee. About 2" from the filler hose tee, I cut the 3/8" hose and installed a 3/8" brass tee I bought from the hardware store for $2.50. The tee was installed so that it was straight through when filling. I then came off the other side of the tee and ran a 3/8" hose from it back to the return fitting on the tank. The purpose of this was "IF" the pump filled the truck tank full (operator error), that when the truck tank and filler hose was full, it would recirculate the fuel back through the return line to the tank. I then installed the ball shut off valve in the tank gravity drain and ran a 3/8" hose through the hole in the side of the bed, left some extra length, capped it off with a bolt in the end, and tied it up to the 2" truck filler hose. The purpose of this was in case the electric pump ever failed, I could pull the 3/8" pump hose off the filler inlet, install the drain hose, open the ball valve, and use the fuel in the auxiliary tank and control it with the ball valve. Obviously it can also be used to drain the tank if needed. The tank vent hose was run through the post hole in the bed rail and left open. This worked out well, as it is protected from the elements, is higher than the tank, and also vented to the outside (I have a cap on my truck). I wired the pump switch so it is only on when the key is on. I also installed the brightest red light I could find, so it comes on when the switch is on. The switch is installed between the 12 volt accessory outlet and the cigarette lighter. This was accessed by pulling off the instrument panel bezel. The system works great and takes about 30 minutes to pump 15 gallons.